fns_dns(5)

NAME

fns_dns– overview of FNS over DNS
implementation

DESCRIPTION

Federated Naming Service (FNS) provides a method
for federating multiple naming services under a single, simple interface
for the basic naming operations. One of the naming services supported by FNS is the Internet Domain Name System, or DNS (see in.named(1M)). DNS is a hierarchical collection of name servers
that provide the Internet community with host and domain name resolution. FNS uses DNS to
name entities globally. Names can be constructed for any enterprise that
is accessible on the Internet; consequently, names can also be constructed
for objects exported by these enterprises.

FNS provides the XFN interface for performing naming resolution on DNS domains and hosts. In addition, enterprise namespaces such
as those served by NIS+ and NIS can be federated with DNS
by adding TXT records to DNS.
To federate an NIS+ or NIS namespace under DNS, you
first obtain the root reference for the NIS+
hierarchy or NIS domain. This reference
is referred to as the nextnamingsystemreference because it refers to the next
naming system beneath the DNS domain. This
reference contains information about how to communicate with the NIS+ or NIS servers
and has the following format:

<domainname> <server name> [ <server address> ]

where <domainname> is the fully qualified domain
name. Notice that NIS+ and NIS have slightly different syntaxes for domain names. For NIS+, the fully qualified domain name is case-insensitive
and terminated by a dot character ('.'). For NIS, the fully qualified domain name is case-sensitive
and is not terminated by a dot character. For
both NIS+ and NIS, <server address> is optional.
If it is not supplied, a host name lookup will be performed to get the machine's
address.

For example, if the machine wiz-nisplus-server
with address 133.33.33.33 serves the NIS+ domain wiz.com., the reference would look
like this:

wiz.com.wiz-nisplus-server133.33.33.33

For NIS, the reference information
is of the form:

<domainname> <server name>

For example, if the machine woz-nis-server serves
the NIS domain Woz.COM,
the reference would look like this:

Woz.COMwoz-nis-server

After obtaining this information, you then edit the DNS table (see in.named(1M))
and add a TXT record with this reference
information. The TXT record must be associated
with a DNS domain that includes an NIS record. For example, the reference information
shown in the examples above would be entered as follows.

For NIS+:

TXT"XFNNISPLUS wiz.com. wiz-nisplus-server
133.33.33.33"

For NIS:

TXT"XFNNIS woz.com woz-nis-server"

Note the mandatory double quotes (' " ')
delimiting the contents of the TXT record.
After making any changes to the DNS table,
you must notify the server by either restarting it or sending it a signal
to reread the table:

#kill-HUP`cat/etc/named.pid`

This update effectively adds the next naming system reference to DNS. You can look up this reference using fnlookup(1) to see if the information
has been added properly. For example, the following command looks up the
next naming system reference of the DNS
domain Wiz.COM:

#fnlookup-v.../Wiz.COM/

Note the mandatory trailing slash ('/').

After this administrative step has been taken, clients outside of
the NIS+ hierarchy or NIS domain can access and perform operations on the contexts in
the NIS+ hierarchy or NIS domain. Foreign NIS+ clients
access the hierarchy as unauthenticated NIS+
clients. Continuing the example above, and assuming that NIS+ is federated underneath the DNS
domain Wiz.COM, you can now list the root of the NIS+ enterprise using the command: